1. Field of the Invention
The present invention relates to a mounting structure for a fuel pump accommodated in a fuel tank of a vehicle engine, and a vehicle including the fuel pump mounting structure.
2. Description of the Related Art
A fuel supply device disposed within a saddle type fuel tank that straddles a body frame is disclosed in Japanese Patent Application Publication No. 2002-106440. A fuel pump mounting structure described in Japanese Patent Application Publication No. 2002-106440 has an opening in a surface located inside of the saddle type fuel tank. A base plate closes the opening. The fuel pump is disposed in an inner space of the tank and mounted such that an axis of the fuel pump extends generally parallel to the base plate. That is, the fuel pump extends along the side surface where the base plate is attached. A filter is coupled with a suction side located at an end portion of the fuel pump, wherein the end portion extends along the axis of the fuel pump.
However, in the fuel pump mounting structure disclosed in Japanese Patent Application Publication No. 2002-106440, the fuel pump is cantilevered against the base plate. That is, the fuel pump is mounted such that an end of the fuel pump is affixed to the base plate, while the other end is not affixed to anything so as to be a free end. Further, the other end extends along the longitudinal axis and the filter is coupled with the other end. Because of this construction, a moment of the cantilever structure (external force pressing the fuel pump and the filter) against the base plate, which is a mounting plate for the fuel pump, can be large. Thus, a rigid mounting plate is necessary to support the fuel pump under a stable condition against the moment. Therefore, the mounting plate can be large, and the fixing structure, such as bolts, for fixing the mounting plate to a tank wall needs to be strengthened. The fixing structure causes an increase in the number of such bolts and increases the fixing time. In addition, the mounting plate needs to be tightly sealed to prevent fuel from leaking.
On the other hand, another fuel supply device for an internal combustion engine is disclosed in Japanese Patent Application Publication No. 2003-74436. A fuel pump mounting structure described in Japanese Patent Application Publication No. 2003-74436 has an opening provided at a top surface of a fuel tank. A fuel pump extends from a bottom surface of a lid that closes the opening and extends vertically therefrom. A suction side located at a distal end of the fuel pump has a filter.
However, the fuel pump mounting structure disclosed in Japanese Patent Application Publication No. 2003-74436 has a construction to support the fuel pump that projects a substantial distance downward from the lid, which is a mounting plate placed on an upper section of the fuel tank for the fuel pump, so as to suck the fuel in from a bottom of the fuel tank. Such a structure, in which the fuel pump extends substantially downward (i.e., in a vertical direction relative to a mounting surface) from the mounting plate of the fuel pump, creates a large moment against the mounting plate, if the mounting plate extends vertically from a side surface of the tank. This structure can cause problems regarding the strength and sealing functions of the mounting plate, similarly to the structure disclosed in Japanese Patent Application Publication No. 2002-106440. Also, the structure of the fuel pump that extends substantially in the vertical direction is not suitable for a bottom surface of the fuel tank.